In recent years electronic thermostats have been introduced in the marketplace in increasing numbers. The early electronic thermostats utilized discrete components in their circuitry, and these components are relatively rugged by comparison to the microelectronic types of devices and integrated circuit chips currently in use. The discrete component versions were generally rugged enough to avoid mechanical damage, as well as being relatively immune to damage from static electric discharges that occur when the device is improperly handled.
The typical electronic thermostat is installed in a home or other area that is carpeted and the generation of static electricity by an individual handling the thermostat has become a severe problem in electronic thermostats that use integrated circuits and similar microelectronics in their circuitry. While electronic thermostats typically are made rugged enough so that mechanical damage is reduced to an acceptable level, the static electric discharges that occur when a person walks across a rug and then handles the thermostat has caused significant damage. Electronic thermostats are normally packed with instructions to protect the unit from static discharges, but these instructions many times are ignored by the installers. In many cases the final owner of a residence that includes an electronic thermostat is not aware of the problems of static discharge in the unit and if the unit is handled without proper care it can be damaged and made unusable.
The present invention recognizes the problems involved and provides a design for an electronic thermostat that mounts the printed circuit board that the electronics are attached to behind a static shield. The static shield is mounted in the thermostat cover with only spring contacts available for interconnection outside of that cover. The spring contacts are recessed in openings that are protected by barriers so that the contact surfaces cannot inadvertently be touched when the cover for the thermostat is handled. The base of the thermostat contains the necessary wiring connections for the thermostat to the external controls, as well as, projecting contacts that mate with the flexible contact surfaces to interconnect to the thermostat circuit in the cover when it is mounted on the base. This mounting is simplified by providing the base means and the cover means each with integral projections that allow the cover to be hinged onto the base and held in place by frictional snaps or detents. This provides for both the electrical connection to the printed circuit board and the retention of the cover on the base. Also, the mounting screws which hold the base in place are thus covered and no screw heads are shown external to the electronic thermostat thereby enhancing its design.